Expandable diaphragm for scrubber atomizer caps

ABSTRACT

An improved atomizer removes deposits from the end cap. The atomizer housing carries a flow of atomizing slurry. A spraying head is connected at one end of the housing and an end cap is connected to the spraying head. A plurality of exit orifices are provided in the end cap for discharging atomized slurry into a flue gas. A connecting ring is detachably engaged with the end cap and has a elastomeric diaphragm for covering an outer surface of the end cap. Energizing fluid is provided through the sprayer head and end cap for expanding the diaphragm away from the end cap surface for releasing particles which adhere to the diaphragm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to the desulfurization offlue gas and, in particular, to a new and useful atomizer cap for a dryscrubber reactor which utilizes an expandable diaphragm.

2. Description of the Related Art

Dry flue gas desulfurization systems such as dry scrubber reactors(DSR's) operate by atomizing an aqueous sorbent (slurry or solution orsolids containing fluid) into a reaction chamber containing hot fluegas, where sulfur dioxide (SO₂) in the flue gas reacts with the sorbentand dries into a powder. Similar systems such as humidification systemsare used to atomize water which contains small amounts of suspended ordissolved solids into a flue gas. The primary methods for atomizing thefluid employ either rotary atomizers or dual-fluid atomizers. One knowndual-fluid atomizer is sold by Babcock & Wilcox under the trademarkDurajet™ which is a dual-fluid type atomizer which has replaced themaintenance-intensive rotary atomizers in some applications.

Dual-fluid atomizer jets entrain surrounding gas that contains a portionof the atomized fluid. The entrained gas flow subsequently establishes arecirculation zone near the atomizer with regions of reverse gas flow.This reverse flow causes fluid droplets to impinge onto the exteriorsurface of the atomizer end cap. This wetting of the atomizer is knownas spray-back. As the water evaporates from the wet atomizer, depositsare formed. If not removed, deposition continues until interferenceoccurs with the atomized jets discharged through the exit orifices,which degrades and deteriorates atomizer performance.

The aircraft industry has used inflatable bladders on critical surfacesof wings for shedding the build-up of ice while in flight.

Presently, the spray-back condition is alleviated by supplying shieldair as an annular flow around the atomizer. The shield air is aimed atpreventing droplets in the recirculating flow from impinging on theatomizer. Testing of known atomizers with water and air as the workingfluids has shown that the shield air helps to minimize spray-back ontothe end cap, but does not prevent end cap wetting downstream of the exitorifices of the atomizer. Moreover, high shield air flow rates candistort the spray pattern, further wetting the end cap, which leads togreater deposit growth in an operating DSR system.

SUMMARY OF THE INVENTION

The present invention is an atomizer for a flue gas desulfurizationreactor comprising an atomizer housing which carries flows of atomizingair and slurry. A spraying head is connected to the housing at one endof the housing. An end cap is connected to the spraying head of thehousing. A plurality of exit orifices are provided in the end cap fordischarging atomized slurry into a hot flue gas. A flexible diaphragm isdetachably engaged to the outer surface of the end cap by a connectingring.

The flexible diaphragm is made of a flexible elastomeric material suchas rubber, neoprene, latex, viton or the like. Energizing fluid such asair is provided through the end cap to the flexible diaphragm forexpanding the diaphragm between its relaxed position and an expandedposition for shedding any particles which had adhered to the outersurface of the flexible diaphragm.

The connecting ring has a plurality of grooves at its innercircumference; and the end cap has a plurality of grooves thereon shapedto receive the grooves of the connecting ring so that the ring can besecured onto the end cap.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a sectional view of a known atomizer;

FIG. 2 is a sectional view of an atomizer according to the presentinvention having a flexible diaphragm in a covering position;

FIG. 3 is a view of FIG. 2 illustrating the flexible diaphragm in anexpanded position;

FIG. 4 is a perspective view of a connecting ring of FIG. 2;

FIG. 5 is a partial perspective view of the end cap of FIG. 2; and

FIG. 6 is a frontal view of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a known atomizer for use for example as a dry flue gasdesulfurization system for atomizing an aqueous sorbent slurry, orsolution of fluid containing solids. The atomizer, generally designated5, comprises an inner barrel 32 disposed within an outer barrel 30 and amixing chamber 36 communicating with the outer barrel 30 and the innerbarrel 32 for mixing of fluid or sorbent provided through the barrels 30and 32 respectively. A spraying head 18 connected at one end of atomizerhousing 5 is used for directing the fluid through exit orifices 24 bysecuring head 18 to flange 20 of outer barrel 30 through screws 22. Anend cap 14 is connected to the spraying head 18 at the one end such thatthe plurality of exit orifices 24 are provided through the end cap 14.Exit orifices 24 lead to the mixing chamber 36 for allowing the fluid tobe sprayed through the exit orifices 24 at the end cap 14. The purposeof streamlining the flow of shield air as it flows along the outersurface of the atomizer is to prevent "spray-back" of the spray liquidslurry onto the atomizer 5.

The same reference numerals are used to designate the same or similarfeatures for the present invention.

The present invention is aimed at removing deposits from the end cap 14of the atomizer 5. FIG. 2 illustrates the end cap 14 having a connectingring 12 detachably engageable with the end cap 14. The connecting ring12 is preferably a metal ring having a flexible diaphragm 10 coveringthe entire area bounded by the ring 12. The connecting ring 12 isconnected over the outer surface of the end cap 14 such that theflexible diaphragm 10 covers a substantial portion of the outer surfaceof the end cap 14 below the exit orifices 24. Thus, any deposits whichform on the end cap 14 below the exit orifices 24, due to spray-backeffects, are adhered to the flexible diaphragm 10 covering the end cap14.

FIG. 4 shows the connecting ring 12 having a plurality of grooves 11 atthe inner circumference of the ring 12. A plurality of grooves 17 on theouter surface of end cap 14, as illustrated in FIG. 5, are shaped toreceive the grooves 11 of the ring 12 so that the connecting ring 12 isdetachably engageable with the end cap 14. The arrangement illustratedin FIGS. 4 and 5 allow for the connecting ring 12 to be screwed onto theend cap 14.

Although FIGS. 4 and 5 illustrate one means for securing the connectingring 12 to end cap 14, this is just one example of a means fordetachably engaging the connecting ring 12 to the end cap 14 and anyother suitable connecting means may be used.

FIG. 6 illustrates another embodiment of the present invention where theflexible diaphragm also surrounds the exit orifices 24 to removedeposition thereon as well.

Diaphragm 10 is made of a flexible or expandable material such asrubber, neoprene, fluoroelastomers, etc. FIG. 2 shows the flexiblediaphragm 10 in a covering position over the cap 14 which receives anydeposits which adhere to the outer surface of diaphragm 10 where theshield air is unreachable and ineffective.

A conduit 13 is provided through the outer barrel flange 20, sprayerhead 18 and end cap 14 as shown in FIGS. 2 and 3. Air conduit 13 leadsdirectly to the flexible diaphragm 10 for providing energizing fluid 16to the flexible diaphragm 10. The energizing fluid 16 passes between thecap screws 22 and the exit orifices 24.

When air 16 is provided through conduit 13 through the spraying head 18and end cap 14 to the diaphragm 10, the energizing air 16 is forcedagainst the flexible diaphragm 10 causing it to expand outwardly fromthe end cap 14 as illustrated in FIG. 3. The air 16 forced between theouter surface of end cap 14 and the inner surface of the flexiblediaphragm 10, causes the flexible diaphragm 10 to be moved to anexpanded position which distorts the shape of the diaphragm 10 whichcauses any deposits adhered to the outer surface of the diaphragm 10 tobe broken free therefrom.

Once the deposits have been broken free from the outer surface ofdiaphragm 10, the energizing fluid 16 is ceased and the diaphragm 10resumes its original shape by returning to the covering positioncovering the outer surface of end cap 14.

The present invention modifies the known atomizer designs, whichprovides several advantages such as providing an efficient method forremoving deposits.

Also, the atomizer does not have to be removed from service to removedeposits thus having minimal effect on the overall desulfurizationprocess.

The diaphragm of the present invention can be remotely controlled, orautomatically operated, thereby reducing maintenance costs. The presentinvention also minimizes the amount of shield air required to preventdroplet impingement.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:
 1. An improved atomizer, comprising:a housing; meansfor channeling a fluid containing solids through the housing; a sprayinghead attached to one end of the housing and constructed to receive thefluid containing solids and directing the fluid containing solids fromthe housing; an end cap connected to the spraying head of the housing,the end cap having an outer surface that receives deposits from thefluid containing solids which adhere thereto; expandable means providedon the outer surface of the end cap for being expanded between a relaxedposition and an expanded position for removing the deposits from the endcap; and means for expanding the expandable means between the relaxedposition and the expanded position, the means for expanding theexpandable means including means for channeling fluid through the endcap to the expandable means.
 2. The atomizer according to claim 1,wherein the expandable means comprises a connecting ring detachablyengageable with the end cap, the connecting ring having an area and anelastomeric material connected to the connecting ring over the area ofthe connecting ring.
 3. The atomizer according to claim 2, wherein theelastomeric material is rubber.
 4. The atomizer according to claim 1,wherein the fluid containing solids is a solution.
 5. The atomizeraccording to claim 1, wherein the fluid containing solids is a slurry.6. The atomizer according to claim 2, wherein the connecting ring has aplurality of grooves at an inner circumference of the connecting ringfor detachably engaging the groove means of the end cap.
 7. The atomizeraccording to claim 2, wherein the elastomeric material is neoprene. 8.The atomizer according to claim 2, wherein the elastomeric material islatex.
 9. The atomizer according to claim 2, wherein the elastomericmaterial is a fluoroelastomer.
 10. The atomizer according to claim 2,wherein the end cap has groove means therein for receiving theconnecting ring.
 11. A method for removing deposits from an end cap ofan atomizer, the method comprising the steps of:providing an atomizerhaving spraying means and an end cap with expansion means attached to anouter surface of the end cap below the spraying means and covering atleast a portion of the end cap; receiving deposits from a fluidcontaining solids on the outer surface of the end cap of the atomizer,the deposits adhering to the outer surface of the end cap; andperiodically expanding the expansion means outwardly from the end capfor removing the deposits adhered to the end cap of the atomizer. 12.The method according to claim 11, including the step of expanding theexpansion means by forcing a fluid into the expansion means of the endcap.